Higher sea temperatures from global warming have already caused major coral bleaching events. Bleaching occurs when corals respond to the stress of warmer temperatures by expelling the colorful algae that live within them. Some coral are able to recover, but too often the coral dies, and the entire ecosystem for which it forms the base, virtually disappears.

Longer-lasting and more extensive bleaching events are already on the rise, with further increases expected in the decades ahead as ocean temperatures continue to rise. Warmer waters are also expected to increase the incidence of other coral diseases such as black band disease, white band disease, white plague, and white pox, all of which can lead to mass mortality of coral, and subsequently the entire ecosystem it supports.